Unlike a traditional flowshop problem where a job is assumed to be indivisible, in the lot-streaming flowshop problem, a job is allowed to overlap its operations between successive machines by splitting it into a numb...Unlike a traditional flowshop problem where a job is assumed to be indivisible, in the lot-streaming flowshop problem, a job is allowed to overlap its operations between successive machines by splitting it into a number of smaller sub-lots and moving the completed portion of the sub-lots to downstream machine. In this way, the production is accelerated. This paper presents a discrete artificial bee colony （DABC） algorithm for a lot-streaming flowshop scheduling problem with total flowtime criterion. Unlike the basic ABC algorithm, the proposed DABC algorithm represents a solution as a discrete job permutation. An efficient initialization scheme based on the extended Nawaz-Enscore-Ham heuristic is utilized to produce an initial population with a certain level of quality and diversity. Employed and onlooker bees generate new solutions in their neighborhood, whereas scout bees generate new solutions by performing insert operator and swap operator to the best solution found so far. Moreover, a simple but effective local search is embedded in the algorithm to enhance local exploitation capability. A comparative experiment is carried out with the existing discrete particle swarm optimization, hybrid genetic algorithm, threshold accepting, simulated annealing and ant colony optimization algorithms based on a total of 160 randomly generated instances. The experimental results show that the proposed DABC algorithm is quite effective for the lot-streaming flowshop with total flowtime criterion in terms of searching quality, robustness and effectiveness. This research provides the references to the optimization research on lot-streaming flowshop.展开更多
This paper introduces a new protocol routing medium access control(RMAC)that integrates the routing and medium access control(MAC)layer protocol.They can both reduce latency and save energy in the wireless sensor netw...This paper introduces a new protocol routing medium access control(RMAC)that integrates the routing and medium access control(MAC)layer protocol.They can both reduce latency and save energy in the wireless sensor network(WSN)while most others propose protocols that sacrifice latency for energy.To make RMAC fit WSN better,we designed an easy and efficient routing protocol base station flooding(BSF)and then integrated it with a MAC protocol timing out MAC(TMAC)[1],while traditionally BSF and TMAC work separately at two layers.We call this two-layer protocol(TLP).We theoretically proved the advan-tages of RMAC over TLP and evaluated RMAC over NS-2.The simulation results show that RMAC spends half the latency of TLP,as well as consumes less energy than TLP.展开更多
基金supported by National Natural Science Foundation of China (Grant Nos. 60973085, 61174187)National Hi-tech Research and Development Program of China (863 Program, Grant No. 2009AA044601)New Century Excellent Talents in University of China (Grant No. NCET-08-0232)
文摘Unlike a traditional flowshop problem where a job is assumed to be indivisible, in the lot-streaming flowshop problem, a job is allowed to overlap its operations between successive machines by splitting it into a number of smaller sub-lots and moving the completed portion of the sub-lots to downstream machine. In this way, the production is accelerated. This paper presents a discrete artificial bee colony （DABC） algorithm for a lot-streaming flowshop scheduling problem with total flowtime criterion. Unlike the basic ABC algorithm, the proposed DABC algorithm represents a solution as a discrete job permutation. An efficient initialization scheme based on the extended Nawaz-Enscore-Ham heuristic is utilized to produce an initial population with a certain level of quality and diversity. Employed and onlooker bees generate new solutions in their neighborhood, whereas scout bees generate new solutions by performing insert operator and swap operator to the best solution found so far. Moreover, a simple but effective local search is embedded in the algorithm to enhance local exploitation capability. A comparative experiment is carried out with the existing discrete particle swarm optimization, hybrid genetic algorithm, threshold accepting, simulated annealing and ant colony optimization algorithms based on a total of 160 randomly generated instances. The experimental results show that the proposed DABC algorithm is quite effective for the lot-streaming flowshop with total flowtime criterion in terms of searching quality, robustness and effectiveness. This research provides the references to the optimization research on lot-streaming flowshop.
基金supported by the National Natural Science Foundation of China(Grant No.60241004 and 60602016)the National Basic Research Program of China(No.2003CB314801)+1 种基金Huawei Foundation(No.YJCB2006062WL)the State Key Laboratory of Networking and Switching Technology.
文摘This paper introduces a new protocol routing medium access control(RMAC)that integrates the routing and medium access control(MAC)layer protocol.They can both reduce latency and save energy in the wireless sensor network(WSN)while most others propose protocols that sacrifice latency for energy.To make RMAC fit WSN better,we designed an easy and efficient routing protocol base station flooding(BSF)and then integrated it with a MAC protocol timing out MAC(TMAC)[1],while traditionally BSF and TMAC work separately at two layers.We call this two-layer protocol(TLP).We theoretically proved the advan-tages of RMAC over TLP and evaluated RMAC over NS-2.The simulation results show that RMAC spends half the latency of TLP,as well as consumes less energy than TLP.
